New procedures will be developed for the rapid synthesis of short oligonucleotide blocks by the triester method which eliminates the necessity of intermediate purification procedures between condensation reactions. These blocks will then be joined together to form hybrid oligonucleotide sequences which are suitable substrates for enzymatic joining. A procedure will be developed for joining together non-overlapping oligonucleotides to form long single strand polynucleotides of defined sequence. The long range goal of this study is to devise faster procedures for the direct synthesis of genes. These methods will ultimately be applied to the synthesis of certain peptide hormone genes.